1-substituted 2, 6-dihalo phenyl hypnotic and analgesic



United States Patent 3,303,092 l-SUBSTITUTED 2,6-D1HALO PHENYL HYPNOTIC AND ANALGESIC Donald E. Stevenson, Herne Bay, Kent, England, assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware No Drawing. Filed June 17, 1963, Ser. No. 288,502 Claims priority, application Great Britain, June 29, 1962, 25,075/ 62 7 Claims. (Cl. 167-52) This invention relates to a method for controlling metabolic processes, particularly for depressing metabolic processes, and especially for the control of pain. The invention provides novel pharmaceutical compositions useful as metabolic depressants, with particular value as hypnotics and as analgesics.

It has been discovered that compounds of the formula following are powerful general metabolic depressants, with hypnotic and analgesic properties, yet are not toxic to animals at the effective dosages and are not known to have undesirable side-effects. These compounds have the formula:

halogenhalogen and salts thereof, wherein halogen represents middle halogen-that is, chlorine or bromine;

Z represents cyano, oxime (CH NOH), alpha-aminooxime (C(amino)=NOH), wherein amino is the amino radical, an alkyl-amino radical of from 1 to 4 carbon atoms or a dialkylamino radical in which each alkyl contains 1 to 4 carbon atoms and thioamide 2))- The salts suitable of the aforesaid compounds may be salts formed with bases or acids according as there are acidic groups, for example, the oxime group =NOH, or basic groups, for example amino and substituted amino groups, respectively, present in the molecule. Where there are no acidic or basic groups, salts will not normally be formed. The preferred salts are the alkali metal, particularly sodium salts, and ammonium and amine salts, especially the diethylamine and triethylamine salts and the mono-, diand tri-alkanolamine salts, particularly the mono-, diand tri-ethanolamine salts, and salts of heterocyclic nitrogenous bases, for example pyridine. Compounds containing basic groups may form salts with organic or inorganic acids, for example, hydrochloric, hydrobromic, sulphuric, phosphoric, nitric, maleic, fumaric, citric, tartaric, methane sulphonic or ethane disulphonic acids.

From the available evidence, it appears that certain genera of this class of compounds are particularly valuable as metabolic depressants. Preferred subgenera are those wherein:

(a) Z is cyanothat is,this subgenus consists of the 2,6- di(middle-halo)benzonitriles, of which 2,6-dichlorobenzonitrile is most preferred;

3,303,092 Patented Feb. 7, 1967 (b) Z is oxime of the formula --CH=NOH, that is,

this subgenus consists of the 2,6-di(n1iddle halo)benzaldoximes, of which 2,6-dichlorobenzaldoxime is most 1 preferred;

(e) Z is alpha-aminooxime of the formula wherein amino is the amino radical, an alkylamino radical of from 1 to 4 carbon atoms or a dialkylamino radical in which each alkyl contains from 1 to 4 carbon atoms, those wherein amino is the amino radical (-NH being particularly preferred, while alphaamino-2,6-dichlorobenzaldoxime is most preferred;

(d) Z is thioamide of the formula -C(S)(N'H with 2,6-dichlorothiobenzamide being most preferred.

Typical species of these compounds include:

2,6-dichlo robenzonitrile; 2-chloro6-methylbenzonitrile; 2-chloro--ethylbenzonitrile; 2,6-dichlorobenzaldoxime;

alkali metal salts alpha-allylamino-2,6-dichlorobenzaldoxime; alphamethylamino-2,-dichlorobenzaldoxime; alpha-dimethylamino-2,6-dichlorobenzaldoxime; alpha-isobutylamino-Z,6-dichlorobenzaldoxime; alpha-amino-Z-chloro 6-bromobenzaldoxime; alpha-amino-2-methyl-6-chlorobenzaldoxin1e and the salts of the above basic substituted benzaldoximes with acids, particularly with the acids hereinbefore specified, 2,6-dichlorothiobenzamide, 2-chloro-6-bromothiobenzamide, and the alkali metal, pyridine, amine and alkanolamine salts of said thiobenzamides; and analogues of the foregoing compounds wherein one or each chlorine atom is replaced by bromine.

The compounds of the general formula hereinbefore specified, and the specific examples given above, depress the spontaneous activity of isolated smooth muscle tissue suspended in a Krebs-Ringer bicarbonate solution, the most active compounds being alpha-amino-2,6-dichl0robenzaldox-ime; alpha-amino-2,6-dichlorobenzaldoxime hydrochloride; 2,6-dichlorothiobenzamide and 2,.6-dichlorobenzonitrile.

The results are summarized in the following table in the section headed In vitro Experiments.

Alpha-amino-2,6-dichlorobenzaldoxime hydrochloride as a 10% wt. solution in water reduced the oxygen consumption of rats by up to 50% when an intraperitonal dose of 200 to 250 milligrams per kilogram body weight was given. The pain threshold and the activity of the central nervous system was simultaneously depressed. Each of the four compounds listed above also produced narcosis in rats following an acute oral dose of a 10% w./v. solution of the compound in dimethyl sulphoxide approaching the lethal range. Symptoms appeared within 2 to 3 minutes and even before consciousness was lost, the animal became unresponsive to painful stimuli. The alpha-amino-2,6-dichloro-benzaldoxime and its hydrochloride were the most active compounds and were approximately equal in activity. The thiobenzamide was somewhat less active. Further tests carried out on similar lines established that 2,6-dichlorobenzonitrile had approximately the same order of activity as 2,6-dichlorobenzaldoxime which was more active than its sodium salt.

Similar effects were obtained with fasting rats by intra-gastrie injection with a ball-point needle of the folrelaxation obtained was of lowing compositions containing the above compounds. 5 produced by such drugs as morphine and pethidine. Ad 2,6 dichi0wbenzonitriiez ministration to rabbits, dogs and cats by intravenous and WJV' solution in dimethyisulphoxide intraperitoneal m ection 1nd1cated that slmilar elfects are 14% w./ V. solution in dimethylsulphoxide p p l In p m one mtlavenous 20% w./v. suspension in aqueous sodium carboxymlectlon of 30 mllhgrafns per lfllogram body Welght methyl cellulose containing 1% wt. of the cellulose 10 duced a State of analgesla sllfficlent to rfimove a.cutaneous derivative granuloma although the animal was still conscious. The Alpha-amino-Z,6-dichlorobenzaldoxime: 10% w./v. soludog able to Walk wlthm mmutes effects tion in dimethylsuiphoxide obtained have proved very consistent. particularly use- Aipha amjno z,6 dichiorobenzaidoxime hydrochloride: ful application of the compositlon of the invention is in the 10% w./v Solution in distilled Water 15 treatment of ruminants where it is feasible to undertake 2,6 dichlorothiobenzamide: 10% w./v. solution in diwlthout the hazard of regurgitation of ruminal conten s. methylsulphoxlde Administration of alpha-amino-Z,6-dichlorobenzaldox- In these tests, the acute Oral tOXlCltY so to rats was ime hydrochloride as a 5% by weight solution in physiofound to be: i logical saline produced rapid sleep in rats, rabbits and in LD5o(m1111gfamS/k'110fmm a dog and eat, when given by intravenous, intra-peritoof y Welght) neal, sub-cutaneous or intra-muscular injection. A dose 2,6-d1chlorobenzon tr1le rate of about 100 milligrams per kilogram body weight p fi- 380 by any of these routes produced rapid sleep, but lower Alphaammo?fi-dlchlombel'lzaldoxlme does rates appeared to inhibit a response to painful hyqfochlorlfiie 749 stimuli. Recovery from an oral dose took 12 to 24 hours 2,6-dlchlorothlobenZamlde Whereas parenteral administration produced a more rapid Animals which had been dosed with the amino response and the animal was fully recovered in 2 to 3 pound or its hydrochloride or with the thiobenzamide re- T COIIIPOUHds are therefore particularly usemained unconscious for 5 to 10 hours depending on the as aflalgetlcs and hypnotlcsslPce depress The dose rate and within 24 hours exhibited a normal degre metabollc rate, they are also useful in cooling body temof activity. The effects of the nitrile were more pro- Pefatufes 1n hypefthel'mla and 1H Produclng Sub-normal longed, lasting some 15 to 24 hours, but the animals ex- Y' P F hibted a normal degree f activity within 48 hours In the following table are summarized the results of Further tests carried out with aipha amino 2 6 d experiments such as described above to determine the chlorobenzaldoxime hydrochloride showed that when ad- I effect of fiichlorobelllonlifilei p qi ministered to rats by intraperitoneal injection at dosages chlorobenzaldoxlme hydrochlorlde and of of 250 milligrams per kilogram body weight, a state of thiobenzamide, in the compositions specified, on specific anaesthesia l d under hi h it was possible t carry body functions and in vitro experiments to determine the out abdominal surgery. Moreover, the degree of muscle 40 eifect of those compounds on isolated tissues and organs. TABLE I IN VIVO EXPERIMENTS 2,6-dichlorobenzonitrile Alpha-amino-Z,fi-dichlorobenzaldoxime Solubility in water 20 p.p.m.

% w. 763 p.p.m.

pH of solution Neutral (saturated solution) pH 2.3 for 10% w. solution N cutral (saturated solution) R AT Dose: 100 mg./kg. b.w. in dlignethyl sulphoxide. Slight transient rise of 10 to 20 mm. Hg. Two further doses of 200 rug/kg. after minute intervals caused 20 mm. Hg fall.

RAT RAT Blood pressure Dose: Jug/kg. of body weight Dose: 200 mgJkg. b.w. in water. (b.w.) in dimethyl sulphoxide. Transient fall 01 20 to 30 mm. Hg Fall from 140 to mm. Hg in duringperiodofanaesthesiainduced period between 2 and 3 hours after by this compound lasting 2 to 3 injection. hours.

Electrocardiogram No significant effect No significant efiect Heartrate do Transient slowing down e.g. 210 to 170 beats per minute.

Respiration Slows down slightly from 60 to 50 No changelnratebut depthdecreased breaths (in+out) per minute from 2 to 3 hours after injection, then restores to normal. Oxygen uptake Not measured Dose of 250 rug/kg. b.w. causes ca. 50% depression lasting 2 to 3 hours. Dose of 200 rug/kg. b.w. causes ca. 20% depression lasting 1% to 2 hours. 00; outp Dose of 250 mgJkg. b.w. causes 40% depression lasting 2 to 3 hours. Dose of 200 mgJkg. b.w. causes ca. 20% depressionlasting 1% to 2 hours.

RABBIT Body temperature-. rln Dose of 100 mgJkg. causes a transient fall of 1 C. between 60 and 90 minutes after injection. Dose of 200 mgJkg. causes a transient fall of 1.4" 0. between 105 and minutes after injection.

No significant effect.

No change. Depressed by dose of 400 gm./kg. b.w. (e.g. from 84 to 68 per minute).

Not measured.

TABLE IContinued IN VIVO EXPERIMENTS COHtiuued 2,6-dich1orobenzonitrile Alpha-amino-2,G-dichlorobenzaldoxlme hydrochloride 2,6-dichlorothiobenzamide Solubility in water 20 p.p.m.

763 p.p.m.

pH of solution Neutral (saturated solution) pH 2.3 for 10% w. solution Neutral (saturated solution) Dluresls Vagal reflex Carotid occlusion Drug response:

To acetylcholine To adrenalin Not measured Unimpaired No change RABBIT Dose of 100 mgJkg. b.w. causes a kidney shut-down between 60 and 105 minutes after injection, when normal diuresis is restored.

RAT

Unimpaired Not measured.

Unirnpaired.

No change.

IN VITRO EXPERIMENTS PERFORMED WITH AQUEOUS SOLUTIONS OF THE CONCENTRATIONS STATED 2,6-dichlorobenzouitrile 2,6-dichlorothiobenzamide Solubility in water SMOOTH MUSCLE Guinea pig ileum Rabbit small intestine Rabbit uterus Guinea pig vas deferens sram'rED MUSCLE MuscleNeuro-muscular junction.

Heart: Rabbit isolated Circulation: Isolated rabbit ear.

20 p.p.m.

pH of solution Neutral (saturated solution) pH 2.3 for w. solution Neutral (saturated solution) Cone, p.p.m.

Effect do Not significantly afiected Not efiected Prefusion showed slightly decreased output.

Initially perfusion caused slight vasodilatation.

Cone, Efiect Cone, Eilect -l gg./m

4 10- Spasrnolysis; contractions 7. 5X10- Spasmolysis abolished conindueed by nicotine, tractions induced by acetylcholine and histaacetylcholine and barium mine are abolished. chloride. Responses Responses restored to restored to normal by normal by washing in washing in Krebs solu- Krebs solution. tion.

4X10- Spasmolysis 7. 5X10- Spasrnolysis. 4 10- do 7. 5X1O- Do. 4X10- Diminished response to 2X10- decrease in response to adrenaline. adrenaline after contact for 5 minutes.

10- Rapidly diminished re- 10- Rapidly diminished response; washing in Krebs sponse; washing in Krebs solution restores to solution restores to normal. normal.

2. 5X10- Perfusion showed no 10- Perfusion shosed no change. change. 2. 5X10- No appreciable effect 10- Perfusion causes slight dilatation; prolonged response to adrenaline.

The preferred compounds to use in the compositions of the invention are alpha-amino-2,6-dichlorobenzaldoxime and its salts, particularly the hydrochloride 2,6- dichlorothiobenzamide and 2,6-dicl1lorothiobenzaldoxime and its sodium salt.

The compositions according to the present invention also comprise a pharmaceutical carrier which may be either a solid material or a liquid. Preparations for oral ingestion can be liquids or solids or any combination of these forms, such as syrups, elixirs, powders or tablets. Preparations for administration of the active agent in unit dose form can take the form of compressed powders or tablets or of a powder enclosed in a suitable capsule of absorbable material such as gelatin. The compressed physiological saline, benzyl alcohol or ethyl oleate and may contain soluble or insoluble diluents and/or solid or liquid excipients.

The unit dosage or the rapeutically effective quantity v of the metabolism control agents of this invention for therapeutic uses described herein can vary over wide" limits. In some cases, as little as 25 milligrams of the active material per kilogram of body weight can be effective, as in the reduction of pain, or in effecting sedation, while seldom will a dosage in excess of about 250 milligrams per kilogram of body weight be required. In general, for oral administration, the effective dosage will be from about 100 to about 200 milligarms per kilogram of body weight, while for parenteral administration, the effective dosage will be from about 25 to about 100 milligrams per kilogram of body weight. Each dosage unit formeach capsule, tablet, ampoule, syrette or prescribed dose-can contain from about 1 percent to about 95 percent of active material, based upon the total weight of the formulation, and preferably contains from about 2.5 percent to about 50% of the active material, on the same basis. Of course, it is possible to administer the therapeutics without the use of a pharmaceutical carrier. The therapeutic agents of this invention can be administered either prior to or after the onset of the condition to be treated, such as when they are used as: analgesics for the amelioration of pain such as the common headache, mild rheumatism and the like; antipyretics to reduce fever or simply to lower the body temperature; motor depressants or tranquilizers to relieve' nervous tension, hyperexcitability and induce sedation; anti-inflammatory agents for edematous conditions such as are caused by arthritis; or as anesthetics for control of pain and/or to relieve muscle tension during an operation.

The invention is illustrated by the following examples of suitable therapeutic compositions in unit dosage form, although it is not intended that the compositions or dosages be limited by any of the proportion, amounts, types or carriers, or dosage units set forth therein.

Example I A solution for injection comprising alpha-amino-2,6- dichlorobenzaldoxime hydrochloride, 5 grams, and distilled water up to 100 milliliters, was prepared by dissolving the hydrochloride in the distilled water, filtering the solution, filling into ampoules and then sterilizing the ampoules in an autoclave.

Similarly, an injectable solution was prepared 'comprising the sodium salt of 2,6-dichlorobenzaldoxime monohydrate as the active ingredient.

Example II Tablets comprising Milligrams 2,6-dichlorothiobenzamide 2.5 Maize starch 10.0

Lactose Stearic Acid 5.0 Sodium carboxymethyl cellulose 0.2

were made by dispersing the sodium carboxymethyl cellulose in Water, mixing this dispersion with the other ingredients except the stearic acid, passing the resulting mixture through a 12 mesh British standard sieve, drying overnight at 70 C., then mixing with the stearic acid and compressing into tablets.

'8 Example III Tablets comprising Milligrams 12,6-dichlorolbenzonitrile 10.0 Lactose 45.5 Starch 24.0

Dextrin' 20.0 Magnesium stearate 0.5

were prepared by mixing the ingredients, other than the vmagnesium stearate, intimately together, passing the mixture through a 60-mesh British standard sieve. After addition of the magnesium stearate, the mixture was granulated and the granules then compressed into tablets.

I claim as my invention:

1. A method of inducing analgesic and hypnotic effects in animals which comprises administering to an animal in pain an effective dosage of a member of the group consisting of a compound of the formula:

hal hal and pharmaceutically acceptable salts thereof, wherein Z represents a member of the group consisting of cyano, oxime (CH=NOH), aplha-aminooxime and thioamide (C(S)(NH hal represents a member of the group consisting of chlorine and bromine.

2. A method of inducing analgesic and hypnotic effects in animals which comprises administering from about 25 milligrams per kilogram of body weight to about 250 milligrams per kilogram of body weight to an animal in pain of a member of the group consisting of a compound of the formula:

hal hal and pharmaceutically acceptable salts thereof, wherein Z represents a member of the group consisting of cyano, oxime (-CH=NOH), alpha-aminooxime (-C (amino)=NOH) in animals which comprises administering to an animal an 1 effective dosage of 2,6-dichlorothiobenzamide.

7. A method of inducing analgesic and hypnotic effects in animals which comprises administering to an animal in pain an effective dosage of 2,6-dich1orobenzonitrile.

References Cited by the Examiner UNITED STATES PATENTS 2,671,798 3/1954 Chamberlin 260-465 3,129,240 4/1964 Hartstra 260-465 3,129,260 4/1964 Yates a 260566 (Other references on following page) 9 FOREIGN PATENTS 862,863 3/1961 Great Britain. 908,964 10/1962 Great Britain.

OTHER REFERENCES Chem. Abst., vol. 58, p. 3362, February 1962, Belgium 612,252.

Derwent: Derwent Belgian Report, No. 68B, C-3, Oct. 18, 1960, citing Belgian 587,164.

Derwent: Derwent Belgian Report, No. 76-A, C-13, citing Belgian 594,573, May 6, 1961.

Derwent: Derwent Belgian Patent Reports, No. 79A, C-l4, Oct. 10, 1961, citing Belgian 598,730.

10 Derwent: Derwent Belgian Reports, No. 91B, 5, General Organic, page 1 (For. Pat. JR 1).

Gass: J. Am. Pharm. Assoc., Sc. Ed., XLVHI, No. 3, March 1959, page 186.

Nature, London, volume 186, pages 89-90, April 2,

Science, Science News Letter, April 16, 1960, p. 249,

vol. 77-78.

JULIAN S. LEVITT, Primary Examiner.

FRANK CACCIAPAGLIA, IR., Examiner.

P. L. SABATINE, JEROME D. GOLDBERG,

Assistant Examiners. 

1. A METHOD OF INDUCING ANALGESIC AND HYPNOTIC EFFECTS IN ANIMALS WHICH COMPRISES ADMISISTERING TO AN ANIMAL IN PAIN AN EFFECTIVE DOSAGE OF A MEMBER OF THE GROUP CONSISTING OF A COMPOUND OF THE FORMULA: 